FR2594558A1 - METHOD AND DEVICE FOR DETERMINING THE APARITION OF REARRANGEMENT PHENOMENA IN THE SOIL - Google Patents

Abstract

In the device comprising a vibrator whose base plate 2 is provided with an acceleration sensor 3 and is resiliently supported by a reaction mass 1 carrying another acceleration sensor 4, the output signal of the sensor 3 is sent. on the one hand to the integrator 6 and on the other hand is weighted by a factor dependent on the mass of the plate 2, the output signal of the sensor 4 is weighted by a factor dependent on the mass 1, the weighted signals of the sensors 3, 4 being sent to an adder 5 whose output signal is multiplied by the output signal of integrator 6 in a multiplier 9 to form a signal controlling the vibrator. Application in particular to the measurement and detection of seismic branching in the ground. (CF DRAWING IN BOPI)

Description

Method and device for determining the appearance of phenomena

  The invention relates first of all to a method for determining the occurrence of rearrangement phenomena in the soil, when a vibrator transmits seismic energy into the ground, as well as a device for the Implementation

of such a method.

  During the last two decades, we have frequently used

  apart from seismology using

  hydraulic vibratory devices for transmitting

  be a seismic energy in the ground so as to explore for example areas that can not be detected by means of explosive seismology. For production

  and the preparation of seismic signals in these soils, we

  pose that elastic processes take place in the soil.

  That is why it is necessary and sufficient to provide

  elastic excitation of the subsoil to transmit energy

  earthquake with as high a return as possible. For this purpose, plates of vibrators, which transmit the seismic energy, are frequently available on off-road trucks.

in the ground.

  With the help of an elevator system, the user is brought

  in the working position, that is to say that

  get on the floor. So that the base plate of the vibrator does not

  do not stand on the ground during vibration, you should apply

  a force that is greater than the intensity of the force of

  brateur. Due to the high pressures, which occur in the vicinity of the vibrator base plate, the stress

  applied to the ground frequently leads to permanent deformation

  nent. In specific cases, this deformation is first of all desirable in order to achieve a preliminary settlement.

  soil to avoid transmission losses. These people

  Transmission is caused by rubbing and rearrangement of the soil in the vicinity of the base plate. To the

  end of the settlement operation, only one more constraint

elasticity is desirable.

  When working on consolidated soils, for example roads, a pre-settlement operation is

  undesirable. Here a settlement can lead to damage

which should be avoided.

  In the case of ground excitation with an ampli-

  vibratory study of the vibrator plate, we can also reach an area in which an elastic deformation leads to a plastic deformation of the subsoil, which

  also leads to soil damage.

  Control of the passage of an elastic deformation

  plastic deformation of the subsoil is therefore

  not only from the point of view of the performance of the exci-

  earthquake, but also with the aim of avoiding

damage to the roadway.

  Modern vibrators provide the ability to measure and control the force applied to the ground. The stress applied to the soil can be evaluated on the basis of this

  dynamic force and in connection with the static load. Un-

  In many road works, the permissible forces can not be precisely indicated, so that a determination of limit values taking into account safety factors can provide a perfect protection.

  damage to the roadway, but a use of

  Efficient vibrators for seismology are no longer possible. Therefore, the purpose of the invention is to indicate a method and a device for determining the appearance of

  rearrangement phenomena in the soil and

  the functioning of the device, to identify the moment

  and the intensity of rearrangement phenomena or other

  riations, absorbing energy, and therefore avoiding

damage to the basement.

  According to a first aspect of the invention, this problem

  resolved with the help of a process to determine the

  of rearrangement phenomena in the soil, when

  brator transmits a seismic energy in the ground, and according to which the energy is transmitted to the ground via a baseplate and said baseplate bears against a reaction mass, characterized in that the - acceleration poses applied to the baseplate of the reaction mass and weighted by the associated mass, adding up the force components that are produced thereby, integrating the component of acceleration of the base plate to form a velocity component and multiplying it by the added force components, and using the continuous part of the output signal obtained from this

  made for the display of the appearance of phenomena of rearrangement

ment.

  In addition, this method is also solved by a

  positive for the implementation of a method for determining the occurrence of rearrangement phenomena in the soil according to

  claim 1, wherein a vibrator transmits an energy

  seismic activity in the soil and in which provision is made

  first acceleration sensor installed on the base plate of the vibrator and another acceleration sensor installed on a reaction mass of the vibrator, against which the base plate bears elastically, characterized in that the output signal of the first acceleration sensor is sent to an integrator and is also weighted, for the formation of a force component, by a mass-dependent factor of the base plate, that the output signal of the other sensor

  acceleration is weighted by a factor that depends on the mass

  reaction and that the weighted output signals of the

  acceleration units installed on the base plate and on the reaction mass are sent, for the formation of the total force component, to an adder, whose signal

  output is multiplied by the output signal of the integra-

in a multiplier.

  With the aid of the process according to the invention, it is possible

  determine the moment at which excitation with an energy

  This value reaches a value that can cause damage in the subsoil. The indication of the active power component of the earth seismic excitation can therefore be advantageously used to determine the limit value

  for which ground excitation is permitted or pos-

  sible without causing damage. The identification of the

  addition of an active power component present in

  the advantage that the reactive power component

  can be used alone in a study

  seismological, can be made maximum.

  The device according to the invention uses

  acceleration sensors mounted on the baseplate and

  firing of the measurement signal from which one can draw the components of force and speed. These components are brought together by means of arithmetic combinations so as to reveal

  as an output signal a measurement value corresponding to

  the active power component of the transmi-

  get in the ground. In vibrators used in practice, the base plate is normally supported against a reaction mass. The force component of the excitation energy

  is therefore determined in this case by means of an addi-

  weighted components of the force components applied to

rentes masses.

  According to an advantageous embodiment variant of

  the invention, the reactive power component can be used.

  tive displayed at the output to control or adjust for example the amplitude of the control signal of the vibrator, so as to

  set a maximum value of the reactive power

tive.

  Other features and advantages of the pre-

  invention will be apparent from the description given hereinafter

  reference in the attached drawing, the single figure of which

  presents a block diagram of the invention.

  The process according to the invention concerns the effect of the soil reaction on the mechanical power. In the case of an elastic reaction without loss of soil, there exists between the pressure and the speed of excitation of the soil which is supposed

  - equal to the vibration speed of the base plate, a

  phasing of 90 ".The phase shift decreases when, in the case of

  elastic movement, a heat appears in the basement.

  In this case the vibrator delivers a dissipated power which

  corresponds precisely to this heating power. If he

  seems in addition to the phenomena of rearrangement in the

  underground or if the resistance limit of the subsoil in the

  seam is exceeded, a mechanical active power is

  issued in addition. Heat output and power

  this active mechanics are undesirable.

  According to the method according to the invention, the

  the force component and the velocity component are obtained at the base plate of the vibrator and are multiplied with each other. The DC component of the output signal as well

  obtained is used to display the appearance of

  rearrangement. The output signal is obtained in the following manner: on the base plate 2 and on the reaction mass 3 are arranged acceleration sensors

  3 and 4, the output signals of which are summed after

  each other by constant factors, which correspond to

  tooth to the ground of the base plate and to the reaction mass.

  F = 1mR. Ari + ImB. aB1 mR = mass of the reaction mass, mB = mass of the base plate, aR = acceleration of the reaction mass,

  aB = acceleration of the base plate.

  The output signal of the adder 5 corresponds

  to the force components of the applied power. This com

  posante is a variable with sinusoidal variation F = F max.cos max wt. The output signal of the acceleration sensor 3 installed on the base plate 2 is furthermore sent to an integrator 6, the output of which delivers the speed signal of the plate

  2. This speed signal is also a significant variable.

  nusoldale corresponding to the following formula V = VBma.cos (wt + B Bmax

  O). The speed component is out of step with the angle t

port to the force component.

  The force and speed components are then

  multiplied between them in a multiplier 9, and we obtain

  the following formula for the instantaneous value of the

  sance: P = F. V = Fmax. cos t. VBmax. cos (t + The output signal corresponds to P = Fmax VBmax (cos + cos (2t + t P = Fax VBm cos ô + F.maxV cos (2cut +) max B max max B max therefore composes, for a constant phase angle, a constant magnitude, which may also be referred to as a reactive power, and a component that oscillates with the angular frequency

double 2x.

  In the case of plastic deformation and

  arrangement of soils, there is a conversion of energy

  which is taken from the system. This power corresponds to the

  measured component of active power, that is to say at the

  posante continues. This is why the latter is equal to: P = 8. F cosf max Bmax The magnitude P therefore constitutes a measurement W of the degree of plastic deformation and rearrangement and by

  consequently a measure of action applied to the soil by the

  F. The reactive power component, represented in this way, of the power transmitted to the ground can be advantageously used not only for display, but also

  for setting or controlling the vibration control signal

  to avoid the production of the active power component and, on the other hand, to maximize the

reactive power component.

  The device according to the invention consists of

  by acceleration sensors 3,4, whose output signals

  are added in the adder 5, after weighting

  by factors corresponding to the masses, in the multipli-

  12 and 13. The weighting may be carried out, for example,

  thanks to the fact that the amplification factors of an ampli-

  the operational indicator used for the addition are

formally to the masses.

  The acceleration component applied to the base plate 2 is furthermore sent to an integrator 6 which can be

  also realized in the form of an operational amplifier.

  The output signals of the adder 5 and the integrator 6 are sent to a multiplier 9 whose output signal can directly provide a measurement, for example the voltage U of the active power component, after separation of

  the reactive power component oscillating with a frequency

this double angular.

  The DC component of the output signal can be separated and displayed electronically or directly

  in a DC voltage device.

  Between the adder 5 and the multiplier 9 or

  the integrator 6 and the multiplier 9 can be inserted

  frequency bands, which can be done under

  the form of low pass filters or in the form of pass filters

  gang. The passing characteristics of filters 7 and 8 can

  It can be controlled by the control signal of the vibrator, so as to provide, during the excitation with the aid of scanning signals, an offset of the data of the filter limit frequencies. Such filters are referred to as

  locking filters. These two filters have a

  the same, so that the phase difference produced by the fil-

  very has the same value for strength and speed.

  The signal can be returned from the output of the

  tiplicator 9 to the control part 11 of the vibrator, so

  to allow automatic control or regulation.

  The different circuits of the device according to

  the invention can be made according to an analog technique.

  than circuits, but one can also use a

  calculation, which is available in a vehicle forming

vibrator device.

Claims (7)

  1. A method for determining the occurrence of   rearrangement processes in the soil, when a trans-   puts a seismic energy in the ground, and according to which the energy   it is transmitted to the ground via a base plate (2) and this base plate bears against a mass   reaction (1), characterized in that the compounds   accelerating forces applied to the baseplate of the mas-   Reaction and weighting by the associated mass, adding up the force components that are produced thereby, integrating the acceleration component of the base plate to form a velocity component and multiply by the added force components, and use the continuous part of the output signal obtained from this   made for the display of the appearance of phenomena of   storage. 2. Method according to claim 1, characterized in that the continuous part of the output signal is used to control by reaction the amplitude of the control signal of the vibrator.   3. Method according to one of claims 1 or 2,   characterized in that the component signals are transmitted   force and speed by means of frequency band filters   quences, whose passing characteristics are controlled   by the frequency of the control signal of the vibrator.   4. Apparatus for carrying out a method for determining the occurrence of rearrangement phenomena in the ground according to claim 1, wherein a vibrator transmits a seismic energy in the ground and in which there is provided a first sensor of acceleration (3) installed on   the vibrator base plate and another accelerator sensor   ration (4) installed on a reaction mass (1) of the vibrator, against which the base plate (2) bears elastically, characterized in that the output signal of the first sensor   acceleration (3) is sent to an integrator (6) and is also   weighted, for the formation of a force component, by a weight-dependent factor of the base plate (2), that the output signal of the other acceleration sensor (4) is weighted by a factor which depends on the reaction mass (1) and that the weighted output signals of the acceleration sensors (3,4) installed on the base plate (2) and on the reaction mass (1) are sent, for the formation of the   total component of force, to an adder (5), whose   output signal is multiplied by the output signal of the inte-   grater (6) in a multiplier (9).   5. Device according to claim 4, characterized   in that the output signal of the multiplier (9) is   sent to the control unit of the vibrator so as to reduce the amplitude of the control signal when a   continuous component that is greater than a threshold value.   6. Device according to claim 4, characterized   in that the signal forming the force component and the   signal from the integrator (6) are delivered by the in-   intermediate of filters (7,8) which depend on the frequency.   7. Device according to claim 6, characterized   in that the filters (7,8) are band-pass filters,   whose passing characteristics are controlled according to   the respective basic frequency of the control signal of the vibrator.